1. Field of the Invention
The present invention relates to a wiring board and its manufacturing method.
2. Discussion of the Background
In Japanese Laid-Open Patent Publication No. 2002-204075, through holes with a coaxial structure are described. In Japanese Laid-Open Patent Publication No. 2002-204075, two plating processes form a coaxial through-hole structure; a plating process for forming an outer through-hole conductor, and a plating process for forming an inner through-hole conductor. Namely, to form an outer through-hole conductor, plating is performed on the inner wall of a penetrating hole for an outer through hole formed in a core substrate, and then, to form an inner through-hole conductor, plating is performed on the inner wall of a penetrating hole for an inner through hole. The contents of Japanese Laid-Open Patent Publication No. 2002-204075 are incorporated herein by reference in their entirety in this application.